(function($){
    $.fn.autogrow = function(options){
        this.filter('textarea').each(function(){
            var $this = $(this),
                minHeight = $this.height(),
                lineHeight = $this.css('lineHeight');
            var shadow = $('<div></div>').css({
                position: 'absolute',
                top: -10000,
                left: -10000,
                width: $(this).width(),
                fontSize: $this.css('fontSize'),
                fontFamily: $this.css('fontFamily'),
                lineHeight: $this.css('lineHeight'),
                resize: 'none'
            }).appendTo(document.body);
            var update = function() {
                var val = this.value.replace(/</g, '&lt;')
                                    .replace(/>/g, '&gt;')
                                    .replace(/&/g, '&amp;')
                                    .replace(/\n/g, '<br/>');
                shadow.html(val);
                $(this).css('height', Math.max(shadow.height() + 20, minHeight));
            }
            $(this).change(update).keyup(update).keydown(update);
            update.apply(this);
        });
        return this;
    }
})(jQuery);